The present invention relates, in general, to a calibration device.
Calibration devices are used, for example, for calibrating extruded continuous profiles, in particular tubes. A plastic melt is hereby initially prepared in an extruder and shaped by an exit nozzle. Following the shaping process so as to assure a desired dimension, the continuous profile travels through the calibration device in which the profile is shaped to accurate size. Production of plastic tubes required heretofore the provision of different calibration devices for varying wall thicknesses or outer diameters. This requires exchange of respective parts, resulting in a shutdown of the machine and thus in downtimes.
German Offenlegungsschrift DE 198 43 340 C2 discloses an overall arrangement for making a plastic tube, including a calibration device which is adjustable to match varying tube diameters and has a plurality of lamellae which are distributed in spaced-apart relationship about the circumference on the outer side of a tube to be calibrated. The lamellae are rounded on their inner side, i.e. the circumferential direction of the tube, in correspondence to a greatest possible outer tube diameter and are combined to individual lamellae groups. Viewed in travel direction of the tube, a plurality of lamellae rims are arranged within a calibrating station, with gaps being provided between the individual lamellae of the individual segment rims so as to allow adjustment of the individual segments in relation to the segments of the next rim or preceding rim.
This conventional calibration device has shortcomings primarily because of the requirement to line up the individual segments in rows so that assembly becomes laborious and thus cost-intensive. Furthermore, unavoidable manufacturing tolerances can add up, so that ultimately proper installation of the lamellae is adversely affected.
It would therefore be desirable and advantageous to provide an improved calibration device which obviates prior art shortcomings and which is simple in structure and easy to assemble and can be made in the absence of excessive manufacturing tolerances.